1. Field of the Invention
The invention relates to optically readable data codes. More particularly, the invention relates to optically readable data encoding which is space efficient.
2. Brief Description of the Prior Art
There are many different types of optically readable data codes in use today. The most common optically readable code is the universal product code (UPC) also known informally as the bar code. The UPC and other bar codes consist of a plurality of vertical lines, horizontally spaced apart. Each line or group of lines represents a digit or alphabetical character. Depending on which bar code is used, meaning is imparted by changing the thickness of the lines, the spacing of the lines, or the height of the lines. In any case, bar codes are written and read linearly, e.g. from left to right. Thus, the amount of data encoded in a bar code is severely limited by the amount of horizontal space available. For example, most bar codes used today encode only about ten digits per linear inch of bar code.
It is therefore an object of the invention to provide methods for encoding data.
It is also an object of the invention to provide methods for encoding data in an optically readable format.
It is another object of the invention to provide methods for encoding data in a compact optically readable format.
In accord with these objects which will be discussed in detail below, the methods according to the invention include arranging dots within a circle such that each dot represents a numeric or alphanumeric digit. The dots are arranged in such a manner that their sequence can be determined.
According to one embodiment of the invention, a circle is divided into nine sectors, each sector representing a different digit. Dots are placed in sectors to indicate digits and connected by lines to indicate the proper sequence of the digits. In this embodiment, the first digit is represented by a large dot and all of the following digits represented by smaller dots. The zero digit is represented by placing a dot on the circumference of the circle. Alignment indicium is preferably provided so that the orientation of the circle can be properly determined. Secondary indicium may be provided to alter the meaning of the sectors, e.g. to distinguish numerical digits from alphabetical characters.
According to a second embodiment, a plurality of circles are arranged concentrically and divided into four quadrants. A numeric or alphanumeric digit value is indicated by a dot on a circle in a quadrant. The number of different digit values which can be represented by a single dot is thus equal to four times the number of circles. Dots are connected by lines to indicate their sequence. Scanning begins at the center of the concentric circle array following a line to the first dot, then follows lines from the first dot to each subsequent dot. Depending on the resolution of the encoding and decoding devices, quite a few dots can be arranged in a single small circular array.
According to a third embodiment of the invention, a plurality of line segments are arranged inside a circle. Each line segment has four portions and each portion has n number of divisions such that each line segment is capable of defining one of 4 n unique data values depending on where a dot is placed on the line segment. The line segments are arranged in an order such that they are read sequentially.
According to a fourth embodiment of the invention, data is encoded in a plurality of circular arrays according to any of the three methods described above and the plural circular arrays are stacked in order to conserve space. When decoding the data, the circular arrays are unstacked and laid out linearly.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.